For the 1837 edition, Joseph Smith deleted the preposition of after because as well as the following relative pronoun which. This kind of original construction using because of is found elsewhere in the text:
The difference here in Ether 1:43 is that the noun phrase after because of is adverbial rather than a direct (or indirect) object. Joseph Smith replaced the original prepositional construction (“because of ”) with the clausal one (“because <finite clause>”), perhaps because he felt uncomfortable with an adverbial noun phrase as the complement of the preposition of. Nonetheless, there is nothing particularly difficult or ungrammatical about the original reading of the text in this passage.
The text has one other strange use of “because of X which …”, and the oddity of this instance has never been removed from the text:
Here in the standard text, the redundant sake along with the genitive s at the end of people’s could be omitted, giving “because of the people who are upon the land” (which is was grammatically emended to who are in the editing for the 1837 edition). The critical text, of course, will retain the original “because of the people’s sake which is upon the land”, despite its difficulty.
Summary: Restore in Ether 1:43 the original nominal construction with because of preceding an adverbial noun phrase; the original reading here is neither difficult nor ungrammatical, although it is unusual.